Shrubby Habit Research Articles

Vernonia proctorii (Asteraceae: Vernonieae), a New Species from Puerto Rico

Recent collections from Puerto Rico have included a heretofore undiscovered species in the large, predominantly tropical genus Vernonia. The new species, V. proctorii in sect. Lepidaploa, subsect. Arborescentes, is a rare element in the shrub forest of the Cerro Mariquita. It is similar to V. albicaulis of Puerto Rico and the Lesser Antilles in capitulescence and involucral features and to V. orbicularis of Cuba in leaf shape. The new species is readily distinguished from the former by its orbicular, sericeous leaves and from the latter by its condensed, cymose capitulescence. For the West Indies, Keeley (1978) counted 42 species of Vernonia Shreber mostly belonging to sect. Lepidaploa (Cass.) DC. subsect. Arbores- centes Ekman, including three species previ- ously known from Puerto Rico. The new taxon described herein, V. proctorii, a fourth Puerto Rican species, is readily attributed to this sub- section because of its shrubby habit, open cy- mose capitulescence, pubescent achenes, and pollen features.

Calea bucaramangensis (Asteraceae), a New Species from the Colombian Andes

Calea bucaramangensis, a radiate species occurring in the Andes of Northeastern Colombia, is described, illustrated, and compared with its nearest allies. Calea L. (Asteraceae: Heliantheae) contains ca. 100 species. Although traditionally placed in Galinsoginae, Robinson et al. (1978) and Rob- inson (1981) suggested that Calea is more closely allied to members of Neurolaeninae. Important features used in the circumscription of Calea are possession of simple, generally opposite leaves, striate phyllaries, ray and disk pappus of free scales, glabrous or glandular and yel- low or white corollas, non-striate, prismatic achenes, and shrubby habit. Species of Calea are common throughout the Neotropics in open, disturbed montane regions. The genus reaches its greatest species diversity in Brazil, the Guayana Highlands, and the Andes. During the investigation of the systematics of Calea in northern South America, three anomalous collections from the Cordillera Ori- ental of the Andes near Bucaramanga were encountered. These collections were made within 50 km of one another and are described here as a new species.

A Systematic Study of the Genus Tetrachyron (Asteraceae: Heliantheae)

Tetrachyron is a genus of five species restricted to eastern Mexico and northern Guatemala. Most previous treatments regard these species as members of various subgenera in the large polymorphic genus Calea. As a result of the various systematic techniques utilized in this study, the genus Tetrachyron is reestablished; it includes the subgenera Tephrocalea and Tetrachyron (in part). Diagnostic features for Tetrachyron are its shrubby habit, opposite, entire to serrulate margined leaves, sol- itary to corymbose capitulescences, and four-angled achenes which usually bear four pappus scales. Generally, these and other morphological, anatomical, and chemical features distinguish Tetrachyron from Calea and other allied genera. Tetrachyron Schlechtendal is a small genus of shrubs that occurs in eastern Mexico and Guatemala. Most species are unknown to the casual observer because of their uncommon occurrence and restricted distri- butions. Tetrachyron never has been studied intensively; the only taxo- nomic treatment produced for it is that by Robinson and Greenman (1896).

A Reconsideration of the Genus Adenolobus (Leguminosae-Caesalpinioideae)

Summary. The genus Adenolobus is considered generically distinct from Bauhinia and shows similarities to the genus Cercis. It occurs in the drier parts of south-western Africa from southern Angola to northern Cape Province, and includes two species, one of which includes two subspecies. Descriptions, synonymy and distribution maps are given and a new subspecific combination is made. The status of a number of genera split off from the broad concept of Bauhinia has been the subject of differing opinions, particularly in the last two decades. Several floristic accounts from tropical Asia and Africa have recognized these segregate genera, while others have argued for lumping some or all back into Bauhinia. The present notes concern one of these minor genera, Adenolobus, which, although given generic status only as recently as 1955, seems to us to be one of the more distinct segregates. Arguments for splitting Bauhinia sensu lato have usually emphasized one or more particularly distinctive features of each individual satellite genus. It has perhaps been under-emphasized that the residue left in Bauhinia in most recent Asian and African accounts has itself one very distinctive feature which seems to hold it together as a natural unit. This is the spathaceous calyx, dehiscing down one side and remaining in one piece for all or nearly all of its length, which is not found in any of the commonly accepted satellite genera. This seems to argue in favour of adopting these segregates, and at the same time argues against the further splitting of Bauhinia which has recently been proposed on mainly palynological evidence by Schmitz (1973)Adenolobus differs from Bauhinia (in the moderately restricted sense) not only in this calyx character but in its fruits which are papery in texture, short and broad but curved and almost semi-lunate, instead of leathery to woody and oblong to linear. It does in fact bear similarities in both calyx and fruit characters to the northern warm-temperate genus Cercis, with which it also shares a resemblance in leaf-shape and-venation, and possession of ten fertile stamens. Furthermore, the general facies of A. garipensis, with its shrubby habit, flowers borne in clusters on very short lateral branches, and three upper petals shorter than the two lower, shows a considerable likeness to the genus Cercis. We suggest that the possibility of close affinity between Adenolobus and Cercis should be examined when the relationships of the genera of the Bauhinieae are reconsidered in future. The geographical separation of the two genera would not be too surprising in view of the wellknown floristic connexion between the dry parts of south-western and northeastern Africa, which is to some extent exemplified by another segregate of Bauhinia sensu lato, Tylosema.

Distribution of two species of birch forming stands on Deeside, Aberdeenshire

Summary A map of the distribution of two species of birch as components of stands on Deeside shows that below the 1,000-foot contour Betula pendula is the dominant species, while above this altitude B. pubescens ssp. odorata becomes dominant. Length and warmth of growing season appear to control the altitudinal limits of dominance and growth of B. pendula. A similar pattern is shown by B. pendula and B. pubescens ssp. tortuosa in Scandinavia. It is postulated that the shrubby growth habit of B. pubescens sspp. odorata and tortuosa is an adaptation to improve the efficiency of solar energy fixation at high altitudes.

Taxonomy of Pericome (Compositae-Peritylinae)

The taxonomy of Pericome (Compositae) is reviewed in connection with recent systematic studies of the subtribe Peritylinae. Included are distributional notes, descriptions, and a key to the two species, P. caudata and P. macrocephala. Two species are recognized for the genus Pericome. Pericome caudata A. Gray is widespread and common in Upper Sonoran to Montane Zones of the southwestern United States, and is also known from Chihuahua, Mexico. The second taxon, P. macrocephala Rob., is known only from its type locality in Durango, Mexico. Rydberg (N. Amer. Fl., 34: 11-29, 1914) placed Pericome in the subtribe Peritylinae (Helenieae). My recent studies of the subtribe have substantiated this disposition, and have suggested that Pericome is closely related to Perityle Benth. (Powell, Sida, 3: 270-278, 1968). This generic affinity is evident in general vegetative and floral morphology, but is particularly expressed through similarities in achene and pappus structure. Pericome is best distinguished from Perityle by its shrubby habit, capitulescence of densely aggregated heads, and coalescent involucral bracts. Pericome plants are the largest of the subtribe, with some reaching a height of nearly 2 m and spreading up to a width of 2 m. PERICOME A. Gray, P1. Wright. 2:81. 1853. Plants subshrubby or herbaceous perennials, 1 m or more high, many-stemmed from the base and spreading, the stems copiously leaved, many-branched especially above, subterete, striate, sparsely puberulent to nearly glabrous except apical branches often densely puberulent to tomentulose; leaves mostly opposite, 5-16 cm long including the petiole, 2-10 cm wide, progressively smaller upwards, blades typically deltoidhastate and long-attenuate (caudate) apically, or less often subhastate, ovate, or cordate and longto short-attenuate, 3-5 lobed, cleft, or 1 Supported by NSF Grants GB-7740 and GB-20361.

Pharmacognostic Study onEcbolium LinneanumKurz Var.DentataClarke

AbstractPharmacognostic characters of Echolium linneanum Kurz (Var. dentata Cl.) having Ayurvedic application in jaundice, menorrhagia, rheumatism, disuria etc. are: 1. Low shrubby habit with woody root stock, bluish bifid flowers in dense spikes, large imbricate 4-ranked bracts oblong lanceolate lamina tapering at both ends and very short petioles; 2. large oval glandular cells with dense contents, on leaf and stem periphery; 3. wood in stem ring porous with mostly solitary pores and with heterogeneous rays (type I of Jane, 1955) containing micro-crystals; 4. internal phloem; 5. leaves with caryophyllaceous stomata; palisade ratio: 4.07 (0.09), stomatal index: 16.52 (± 1.10) and vein-islet number: 7.00 (0.21); 6. roots with abundant thick-walled fibres in secondary xylem.